1. Field of the Invention
The present invention relates to a fluororubber composition. More particularly, the present invention relates to a rubber composition comprising a fluororubber and a diene or polyolefin base rubber, which composition has good compatibility and can provide a cured material having good chemical resistance, heat resistance and oil resistance at a low cost.
2. Description of the Related Art
A fluororubber has the best properties such as solvent resistance, heat resistance, chemical resistance or weather resistance among various rubbers. Since requirements for the properties of these rubbers have recently become more and more severe, a demand for the fluororubber is increasing.
However, the fluororubber has a large specific gravity and is very expensive, its application is limited.
To overcome such a drawback of the fluororubber, various proposals have been made for blending general rubbers with the fluororubber. For example, Japanese Patent Kokai Publication Nos. 50050/1080 and 101135/1985 disclose techniques for improving co-crosslinking properties of the rubbers, and Japanese Patent Kokai Publication No. 135843/1982 discloses a technique for improving the compatibility of the rubbers.
When the properties of the rubber blend are compared with those of the fluororubber as such, properties of recessive rubbers dominate so that the blend does not necessarily have the desired properties. This means that the co-crosslinking type polymer blend or the microdispersion technique is not satisfactory.